Note 4 - Loans and Allowance for Loan Losses - Loans by Credit Risk Rating, Segregated by Class of Loans (Details) - USD ($) $ in Thousands		Dec. 31, 2016	Dec. 31, 2015
Balance, end of period		$ 5,632,890	$ 4,919,355
Loans acquired	[1]	1,305,683	1,672,901
Pass [Member]
Balance, end of period		5,433,036	4,745,322
Loans acquired		1,217,886	1,590,384
Special Mention [Member]
Balance, end of period		33,865	20,334
Loans acquired		22,181	9,150
Substandard [Member]
Balance, end of period		164,251	148,719
Loans acquired		64,075	69,219
Doubtful [Member]
Balance, end of period		1,715	4,521
Loans acquired		1,541	3,689
Unlikely to be Collected Financing Receivable [Member]
Balance, end of period		23	459
Loans acquired			459
Consumer Portfolio Segment [Member]
Balance, end of period		488,563	385,668
Consumer Portfolio Segment [Member] | Pass [Member]
Balance, end of period		485,575	383,878
Consumer Portfolio Segment [Member] | Special Mention [Member]
Balance, end of period		26
Consumer Portfolio Segment [Member] | Substandard [Member]
Balance, end of period		2,962	1,741
Consumer Portfolio Segment [Member] | Doubtful [Member]
Balance, end of period			49
Consumer Portfolio Segment [Member] | Unlikely to be Collected Financing Receivable [Member]
Balance, end of period
Consumer Portfolio Segment [Member] | Credit Card Receivable [Member]
Balance, end of period		184,591	177,288
Consumer Portfolio Segment [Member] | Credit Card Receivable [Member] | Pass [Member]
Balance, end of period		183,943	176,809
Consumer Portfolio Segment [Member] | Credit Card Receivable [Member] | Special Mention [Member]
Balance, end of period
Consumer Portfolio Segment [Member] | Credit Card Receivable [Member] | Substandard [Member]
Balance, end of period		648	479
Consumer Portfolio Segment [Member] | Credit Card Receivable [Member] | Doubtful [Member]
Balance, end of period
Consumer Portfolio Segment [Member] | Credit Card Receivable [Member] | Unlikely to be Collected Financing Receivable [Member]
Balance, end of period
Consumer Portfolio Segment [Member] | Other Loans [Member]
Balance, end of period		303,972	208,380
Consumer Portfolio Segment [Member] | Other Loans [Member] | Pass [Member]
Balance, end of period		301,632	207,069
Consumer Portfolio Segment [Member] | Other Loans [Member] | Special Mention [Member]
Balance, end of period		26
Consumer Portfolio Segment [Member] | Other Loans [Member] | Substandard [Member]
Balance, end of period		2,314	1,262
Consumer Portfolio Segment [Member] | Other Loans [Member] | Doubtful [Member]
Balance, end of period			49
Consumer Portfolio Segment [Member] | Other Loans [Member] | Unlikely to be Collected Financing Receivable [Member]
Balance, end of period
Commercial Real Estate Portfolio Segment [Member]
Balance, end of period		3,028,079	2,204,992
Commercial Real Estate Portfolio Segment [Member] | Pass [Member]
Balance, end of period		2,943,890	2,128,687
Commercial Real Estate Portfolio Segment [Member] | Special Mention [Member]
Balance, end of period		10,996	8,424
Commercial Real Estate Portfolio Segment [Member] | Substandard [Member]
Balance, end of period		73,019	67,104
Commercial Real Estate Portfolio Segment [Member] | Doubtful [Member]
Balance, end of period		174	777
Commercial Real Estate Portfolio Segment [Member] | Unlikely to be Collected Financing Receivable [Member]
Balance, end of period
Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member]
Balance, end of period		336,759	279,740
Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member] | Pass [Member]
Balance, end of period		330,080	270,386
Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member] | Special Mention [Member]
Balance, end of period		98	319
Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member] | Substandard [Member]
Balance, end of period		6,565	9,019
Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member] | Doubtful [Member]
Balance, end of period		16	16
Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member] | Unlikely to be Collected Financing Receivable [Member]
Balance, end of period
Commercial Real Estate Portfolio Segment [Member] | Single Family Residential Loans [Member]
Balance, end of period		904,245	696,180
Commercial Real Estate Portfolio Segment [Member] | Single Family Residential Loans [Member] | Pass [Member]
Balance, end of period		875,603	679,484
Commercial Real Estate Portfolio Segment [Member] | Single Family Residential Loans [Member] | Special Mention [Member]
Balance, end of period		4,024	2,701
Commercial Real Estate Portfolio Segment [Member] | Single Family Residential Loans [Member] | Substandard [Member]
Balance, end of period		24,460	13,824
Commercial Real Estate Portfolio Segment [Member] | Single Family Residential Loans [Member] | Doubtful [Member]
Balance, end of period		158	171
Commercial Real Estate Portfolio Segment [Member] | Single Family Residential Loans [Member] | Unlikely to be Collected Financing Receivable [Member]
Balance, end of period
Commercial Real Estate Portfolio Segment [Member] | Other Commercial Loans [Member]
Balance, end of period		1,787,075	1,229,072
Commercial Real Estate Portfolio Segment [Member] | Other Commercial Loans [Member] | Pass [Member]
Balance, end of period		1,738,207	1,178,817
Commercial Real Estate Portfolio Segment [Member] | Other Commercial Loans [Member] | Special Mention [Member]
Balance, end of period		6,874	5,404
Commercial Real Estate Portfolio Segment [Member] | Other Commercial Loans [Member] | Substandard [Member]
Balance, end of period		41,994	44,261
Commercial Real Estate Portfolio Segment [Member] | Other Commercial Loans [Member] | Doubtful [Member]
Balance, end of period			590
Commercial Real Estate Portfolio Segment [Member] | Other Commercial Loans [Member] | Unlikely to be Collected Financing Receivable [Member]
Balance, end of period
Commercial Portfolio Segment [Member]
Balance, end of period		789,903	648,679
Commercial Portfolio Segment [Member] | Pass [Member]
Balance, end of period		765,023	635,351
Commercial Portfolio Segment [Member] | Special Mention [Member]
Balance, end of period		662	2,760
Commercial Portfolio Segment [Member] | Substandard [Member]
Balance, end of period		24,195	10,562
Commercial Portfolio Segment [Member] | Doubtful [Member]
Balance, end of period			6
Commercial Portfolio Segment [Member] | Unlikely to be Collected Financing Receivable [Member]
Balance, end of period		23
Commercial Portfolio Segment [Member] | Commercial Loans [Member]
Balance, end of period		639,525	500,116
Commercial Portfolio Segment [Member] | Commercial Loans [Member] | Pass [Member]
Balance, end of period		616,805	487,563
Commercial Portfolio Segment [Member] | Commercial Loans [Member] | Special Mention [Member]
Balance, end of period		558	2,760
Commercial Portfolio Segment [Member] | Commercial Loans [Member] | Substandard [Member]
Balance, end of period		22,162	9,787
Commercial Portfolio Segment [Member] | Commercial Loans [Member] | Doubtful [Member]
Balance, end of period			6
Commercial Portfolio Segment [Member] | Commercial Loans [Member] | Unlikely to be Collected Financing Receivable [Member]
Balance, end of period
Commercial Portfolio Segment [Member] | Agricultural Loans [Member]
Balance, end of period		150,378	148,563
Commercial Portfolio Segment [Member] | Agricultural Loans [Member] | Pass [Member]
Balance, end of period		148,218	147,788
Commercial Portfolio Segment [Member] | Agricultural Loans [Member] | Special Mention [Member]
Balance, end of period		104
Commercial Portfolio Segment [Member] | Agricultural Loans [Member] | Substandard [Member]
Balance, end of period		2,033	775
Commercial Portfolio Segment [Member] | Agricultural Loans [Member] | Doubtful [Member]
Balance, end of period
Commercial Portfolio Segment [Member] | Agricultural Loans [Member] | Unlikely to be Collected Financing Receivable [Member]
Balance, end of period		23
Unallocated Financing Receivables [Member]
Balance, end of period		20,662	7,115
Unallocated Financing Receivables [Member] | Pass [Member]
Balance, end of period		20,662	7,022
Unallocated Financing Receivables [Member] | Special Mention [Member]
Balance, end of period
Unallocated Financing Receivables [Member] | Substandard [Member]
Balance, end of period			93
Unallocated Financing Receivables [Member] | Doubtful [Member]
Balance, end of period
Unallocated Financing Receivables [Member] | Unlikely to be Collected Financing Receivable [Member]
Balance, end of period

[1] See Note 5, Loans Acquired, for segregation of loans acquired by loan class.